Rabbit behavior question

[evilpettingz00]

Hello!  I put an igloo (this sort of thing) in my rabbit's cage and he spends a lot of time flipping it on its side or upside-down.  He never leaves it right-side up even though my other rabbit at least seems to appreciate it that way.  From this behavior, should I assume that he's most likely thinking:
A.  Flipping things over is fun!  Thanks for this!
B.  I prefer this upside-down, thank you.
C.  I don't like this here!  Get rid of it!
or D.  Other.  What?

Thanks!